The present invention relates to a process for charging at least one free-flowing component with gas in the preparation of cellular plastics from at least two free-flowing reaction components. The gas is metered into a hollow stirrer from the outside, sucked in by it and is dispersed into the component in a gassing chamber.
In order to achieve certain properties in such plastics, it is necessary to charge at least one component with gas, for example air. The quality of the properties desired in the end product very largely depends on the dispersion and homogenization of the gas in the component. Such processes are used in particular in the preparation of preferably foamed polyurethane plastics, polyisocyanurate plastics and polyurea plastics. Dispersion of the gas into the component in a gassing tank provided with a hollow stirrer, with the gassing tank being intermediately positioned in a line leading from the storage tank to the mix head, is known from German Offenlegungsschrift No. 3,434,443. The stirrer blades of the hollow stirrer and/or the stirrer speed thereof are adjustable, so that a desired amount of gas per unit time can be sucked in. Other gassing processes with hollow stirrers are known and are described in published European application Nos. 110,244 and 175,252, and in German Offenlegungsschrift No. 3,434,444.
All the above processes have the deficiency that the dispersion and homogenization of the gas in the component is not adequate, which manifests itself in particular in the gassing of highly viscous components and with sparingly soluble gases.
An object of the present invention was to improve the processes of the above-mentioned type to the extent that the degree of dispersion of the gas in the component and the rate of solution are increased. At the same time, it was an object to allow the the devices of the above type to be used successfully for components of relatively high viscosity.